Attempt to blast the dam starts; 8 killed, many more at missing, at risk;

Google map of the location, the landslide location seems just upstream of the dam

A massive landslide at around 2.30 am on Aug 2, 2014 has blocked the flow of the river Sunkoshi in Nepal. Twelve hours later and after first failed attempt by the Nepali army to blast the artificial dam, the reservoir behind the dam continues to swell. Already eight people have been confirmed dead, over 300 are reported missing[1]. Many more are at risk in the downstream Nepal and further downstream India. Sunami Power house has already been inundated. The Landslide seems close to an existing dam on the river. If this is true, when the landslide dam bursts either due to the army efforts or due to the water pressure, it is likely to take the dam with it and this could increase the downstream impacts.

A view of the landslide dam photo courtesy Setopati.com

Prof David Petley wrote to SANDRP about this: “It is very dangerous indeed. I know this site very well as we have been working in that valley for a decade or so. I suspect that the breach will happen quite quickly and will be very damaging.”

“Bishyari much more devastating than GLOFs” Former Water Resources Minister and well known water expert Dipak Gyawali told SANDRP: “Bishyari is the Nepali word for this kind of a “landslide dammed lake outburst flood” much more devastating than the GLOFs . This is a geo-hydrological phenomenon and as the pictures show, brings down entire mountains with thick forests on them. This one was on an old landslide still active but exacerbated by the recent spate of hydropower as well as road blasting.” Jayanta Bandyopadhyay and Dipak Gyawali were the first to put the word ‘bishyari’ in English, in a 1994 much-quoted article in Mountain Research and Development.

Massive scale of the landslide dam, photo thanks to Kathmandu Post

Indian border is about 260 kilometers downstream from the landslide when measured along the river and on the way there is also the Kosi Barrage at Bhaimanagar / Rajbiraj (correction from earlier reported distance).

A view of the massive landslide dam, photo courtesy Nepalhub.com

This morning, an email from our friend Ratan Bhandari from Kathmandu informed of this development, and it seems like a bad news to precede Indian Prime Minister Narendra Modi’s visit to Nepal, but it could also be a timely wake up call not to go for massive interventions in the Himalayan states.

Rising reservoir behind landslide on Sunkoshi river, Nepalhub.com

The massive landslide blocked Sunkoshi River at Mankha VDC in Sindhupalchowk[2] district. Around two dozens houses were buried in the landslide. The landslide has also buried Arniko Highway at Dam Site in Mankha VDC. Locals in Barhabishe, Lamesanghu, Khadichaur, Dolalghat, among other surrounding areas have moved to safety fearing that the blocked river may burst anytime. A Nepal Army chopper has been deployed to intensify the rescue work. The government has mobilized security forces to break a landslide dam that has blocked the flow of water in Sunkoshi River[3] in Jure of Mankha VDC, Sindhupalchowk.

A view of the dam and the river, photo courtesy Setopati.com

The Central Natural Disaster Relief Committee (CNDRC) has asked the Ministry of Home Affairs[4] to declare the areas downstream the blocked Sunkoshi River, from Jure of Sindhupalchok to Nepal-India border, “crisis-hit region” as the threat of outburst floods loomed large. It is hoped that the Indian authorities in downstream Indian areas are alert and doing necessary steps for the protection of life and property in India.

Landslide and the dam photo courtesy onlinekhabar.com

According to the Ministry of Home Affairs, the water level rose to above 130 metres. About 100 houses on the bank of the river have been submerged in Jure of Ramche VDC-5[5], the Araniko highway itself has been blocked.

Houses affected by landslide, photo courtesy onlinekhabar.com

The Sunima hydropower project (constructed in 2004-5) that has already been inundated is a 2.6 MW project built by Himal Hydro[6]. The dam of the 10.5 MW Sunkoshi hydro project (completed in 1972 with Chinese aid) is immediately downstream from the landslide, and is likely to face damage along with its power station further downstream whenever the dam breaches.

A view of Sanima Power House in Sindhupalchok, photo courtsy Himalayan Times, Nepal

Dr David Petley, who has traveled in the area writes in his blog[7]: “However, it is now a crisis. In the peak of monsoon season the river flow is high, and the images show that the lake is filling quickly. The images suggest that there is no reason to be confident that the dam will not breach rapidly when overtopped – indeed, quite the opposite I think as the length of the dam is not large and the materials appear to be fine grained. A breach now could generate a very large flood; when full the effects could be very serious… So what to do? Well of course the first measure is to evacuate people downstream, and this has started. The second is to put a warning system in place, probably at this stage consisting of an observation team with appropriate communications. The third will be to start to excavate a channel, which will require heavy machinery… This is a very difficult problem to manage, so Nepal should seek international help. The best qualified people are the teams that dealt with the valley blocking landslide crisis after the Wenchuan earthquake in China. Given the strategic importance of this road, the Chinese may want to help. However, time is very limited.”

About the possible causes of the massive landslide, this article says it is partly due to the after effects of last year’s landslide at the same site: http://www.myrepublica.com/portal/index.php?action=news_details&news_id=80211.

It also says that the district has seen such landslide blocked rivers causing disasters in the past too including the ones in 1982 (in Balephi village of the district when 97 people had lost their lives) and 1996 (54 people had died due to a landslide caused by dam outburst flood in Larcha, another village of the district).

A view of the blocked Sunkoshi River in Sindhupalchok, Photo courtesy Himalayan Times Nepal

We hope all such necessary steps are urgently taken and Indian government, Bihar state government and Nepal government coordinates in this on urgent basis.

A man taking a photo of the artificial lake formed due to Sunkoshi River Blockade in Sindhupalchok

Himanshu Thakkar, SANDRP

PS: According to http://hydrology.gov.np/new/bull3/index.php/hydrology/station/graph_view?stationId=104&deviceId=91&categoryId=6, the inflow is about 150 cubic meters per second, so in 11 hrs the volume stored would be about 6 million cubic meters. The impact on the downstream would depend on the way this water gets released. (This link thanks to comment on Dave Petley blog.) The lake overflow could have just started at around 1.30 Indian Std Time, but it is not clear what is the outflow rate.

PS 2: Comments from Dr Dinesh Kumar Mishra:
A. Flood warning has already being issued by the district administration in Saharsa about 3 hours ago that there is an imminent danger of floods along the embankment and the most vulnerable point is the site of 1984 breach.

Map with orange line showing the path that the flood pulse from the landslide dam will take to reach Kosi in India, FMIS map

B. There is some activity at the Bhimnagar barrage with officials and engineers keeping an eye over the situation. I am told that the Government has asked its officers of the Kosi Project at Birpur to move to safer places. Otherwise, there is calm at Birpur.

C. I have just received a message from a friend of mine from village Bela in Marauna block of Supaul district (this village is located within the Kosi embankments) and they have not received any warning from the Government and only know that something odd has happened in Nepal.

D. Villages near Madhepur block along the western embankment of the Kosi have not received any warning. They are not aware if anything wrong has happened in Nepal.

PS 3: Just (1600 hrs) called Control Room of NDMA (ph no: 011 26701728) and Mr Kulwinder informed me that Nepal govt informed NDMA at 1136 hrs about this and NDMA in turn has alerted Bihar Govt, Home Ministry, Cabinet Secretariat and others, he said PMO would also be aware of this when I told him PM is going to Nepal tomorrow. They have kept 9th NDRF battalion at Patna/ Kolkata on alert. He was aware that Koshi would be affected. He is not aware of any cooperation from Indian side on this.

PS 4: 1730 hrs: According to reliable sources, there is debate between Nepalese authorities saying that all the gates of the Koshi barrage should be kept open for the flood wave to safely pass and elements on Indian side that, that should wait for the flood wave to come. A contingent of senior officials are being airdropped to the barrage site with letter from CM. The second blast at the landslide dam in the meantime managed to lower the upstream reservoir water level by 2 m, but it is not clear if the outflow is continuing or has stopped.

1820 hrs: All 56 gates of Kosi Barrage have been opened, good to see that better sense have prevailed.

(Nepali time 4:00 pm) “The Sunkoshi River has started to flow after Nepal Army (NA) detonated two explosives. The water volume in the river downstream has increased as compared to the regular one. Authorities believe resumption of river flow will put off possible damages.” The landslide dam has created reservoir of 90-100 m height.

From: http://www.myrepublica.com/portal/index.php?action=news_details&news_id=80184
“Three eastern districts, Sunsari, Saptari and Udayapur have maintained high alert to remain safe from the possible Saptakoshi River inundation. The local administration has already begun its task to alert the people of riverside in Sunsari to shift them to safer places while the administration in Udaypur and Saptari districts have made arrangements to inform people about the blockage of river and aware people about the possible flooding, said Sharma. It is possible that as many as 500 VDCs in the districts and Bihar State of India would be inundated if the blocked landslide debris opened at once and the Koshi barrage was damaged.”

“Some 14 VDCs in Khotang district are at high risk of inundation after the landslide in Sindhupalchok district blocked the passage of Bhote Koshi River. Bahunidanda, Dikuwa, Chyasmitar, Durchhim, Dhitung, Rajapani, Batase, Chichkiramche, Barahapokhari, Saunechaur, Suntale and other VDC that are on the side of Sunkoshi river are at high risk of flooding. The District Administration Office and District Police Office have urged the locals to shift in the safe areas to remain away from the possible risks. Assistant Chief District Officer Arjun Rai said that the locals of the low land site have been asked to move to higher ground. ”

“‘Sri Lanka tapu’, which lies in middle of Sapta Koshi River, has been declared flood crisis zone in view of possible flash flood caused by likely bursting of artificial lake formed by landslide in Sunkoshi River. Local administration declared the area flood crisis zone which has settlements of over 12,000 persons on Saturday. Security personnel along with government and non-government organizations have been deployed to aware and shift locals to safer places in east and west of the island which is home to indigenous nationalities of Tarai and Hilly regions. Chief District Officer Sudarshan Prasad Dhakal said that security agencies have been directed to shift children and elders along with valuables to a safer place. Local administration has also urged people in seven other VDCs— Barahachhetra, Mahendra Nagar, Prakashpur, Madhuban, Paschim Kusahawa, Shreepur and Haripur— to move to a safer place. The possible flash flood will reach Sapta Koshi barrage in around 10 hours, and all 56 floodgates have been opened in view of possible danger, informed CDO Dhakal. ”

“…two iron gates, which diverted water to intake of Sunkoshi Hydropower Project (10 megawatts), was swept away by flood in the wee hours on Saturday morning… Similarly, power supply from 45 megawatts Upper Bhotekoshi Hydropower Project has also been disrupted… Likewise, 11 kV transmission line for evacuating power from Chaku Khola (total 6 megawatts) and Bhairab Kunda (3 megawatts) and another 33kV transmission line for evacuating power from Sunkoshi Hydropower Project (10 megawatts) has also been damaged… Officials at Load Dispatch Center of NEA also said Sunkoshi River flooding may breach dams and affect power supply from Khimti Hydropower Project and others hydropower projects on the Tamakoshi River basin.”

“The Central Water Commission has estimated a discharge of 14 lakh cusecs of water but the Indian embassy in Kathmandu has informed the National Disaster Management Authority about the likely discharge of 25 lakh cusecs of water post blast. In either case, 40% of the discharge will gush into Bihar.

The water will take about 12 hours to hit the Kosi barrage which has the capacity of sustaining pressure of only eight lakh cusecs. The flood, if it occurs, would affect a population of 1.5 lakh in Bihar’s eight districts, including 50,000 people in 22 panchayats of Supaul district alone.”

It is well known that Kosi embankment breached in Aug 2008 when flow was below 1.5 lakh cusecs, so even if barrage is able to take 8 lakh cusecs (seems unlikely), embankment is likely breached at much lower flows.

“As the dam resulting from the landslide grew larger by the hour, at least three human settlements became submerged. Damsite bazaar in Mankha-1, Kagune village in Mankha-5 and another settlement in Tekanpur-5 vanished into the water. Security personnel rescued 16 people from Damsite and seven from Tekanpur villages before these became submerged; no one was rescued from Kagune village.

According to Sindhupalchok District Police Office, 26 houses at Damsite, 16 at Kagune and seven houses at Tekanpur disappeared. At Damsite, a school was also buried under the landslide-induced dam.

Local authorities say explosions set off by the NA have slightly reduced the risk of flood outburst. “The risk has been reduced,” said Chief District Officer Gopal Prasad Parajuli. “The water volume in the landslide-induced dam is declining. The blocked water is now flowing through the small channels created by the explosions, albeit only partially.””

A view of water flowing out of landslide dam, photo from myrepublica.com

The last para is good news since it seems to suggest (as can also be seen from above photo) that water has slowly started flowing out and hopefully there is no more accumulation, but slow depletion.

This is good to know: “‘Outflow of water normal“: Meanwhile, the Sunkoshi River is flowing out of the lake in a controlled rate today, according to the National Emergency Operation Centre (NEOC) of the Ministry of Home Affairs. Water level has not decreased significantly as the volume rate of water flowing in and out of the lake are comparable.”

The same report claims: “According to an official at the NEOC, about half of the chunk of debris that obstructed the River has been destroyed by the controlled blasts to drain out the water.” This is somewhat difficult to understand.

“Parajuli said the amount of water flowing out of the dam and pouring in was almost the same on Sunday morning, keeping the water level stable.” This seems to indicate STATUS QUO at Landslide Dam on Sunday evening?

This paints a bit scary possibility: “Vyasji and minister for water resources, Vijay Kumar Choudhary said, while the barrage is designed to withstand a pressure upto 9lakh cusecs, the highest pressure it has faced is 6 lakh cusecs. Anything above that could be a worry. Around two lakh people living within the embankments on a 256 km stretch from Birpur to Naugacchia and Khagaria near the Ganga would be in the direct path of the feared cascade, once Nepal effects an explosion to release the Sun Kosi waters. To add, the river has a gradient of 47 metres per kilometre in its upper reaches and flattens to only 1 metre per km after Chatra in Nepal. Beyond Chatra, on account of a progressive flattening of the bed gradient, the river first deposits boulders, pebble and shingles for over a distance of 32 km and sediment loads upto Hanumanagar. Officials fear, if the some estimated 27 lakh cusecs is released suddenly, these boulders could hit the Birpur barrage and cause extensive damage forcing it to give way. That would be an unprecedented disaster, the likes of which India has never seen, compromising as it would some 5 lakh people downstream, all the way upto the Ganga, some 80 km south in a straight line.”

AVOIDABLE TRAGEDY? “Ajay Dixit, a water expert is as baffled as Professor Narendra Khanal at the Central Department of Geography at Tribhuvan University as to what triggered the landslide. The slope is prone to landslide as portion of debris used to fall every year. What they both knew for sure is an oversight of the government. “We totally overlooked the need to monitor such disaster-prone areas, which is not a big deal these days,” said Khanal. He said the disaster is unpredictable but mitigation measures can help avert huge loss.”

This provides some clearer picture: The landslide dam now has about 15 million cubic meters of water (much more than 6 MCM earlier estimated), that the water level is gradually reducing, it has already reduced by 3 mts from peak. “Since the landslide has not stopped completely yet, there is still the risk of Landslide Dam Outburst Flood (LDOF).” That would create BIG disaster in the downstream areas. However, there are serious doubts if the volume is 15 MCM as noted here.

Ranjan Kumar Dahal, a geologist who visited the landslide area along with Home Minister Bam Dev Gautam on Sunday, said, “If another landslide occurs in the same area, the impact could be catastrophic.” Dahal said the upper part of the mountain where the massive landslide occurred is vulnerable to more landslides. “There are cracks,” said he. “So, a little rain could lead to more landslides.”

Very interesting blog from well known Nepal Journalist Kunda Dixit, it says: The landslide zone is about 1000 m high, 500 m wide and has piled up a 100 m high dam on the river bed and the impact was so huge that it has also taken forested area from opposite bank. “In 1981, nearly 20 km of the Arniko Highway and all its bridges were washed away, the Sun Kosi power house was seriously damaged and there was loss of life and property all the way down the valley. Everyone thought it was a monsoon flood, but the event was later traced to a glacial lake high up on the northern side of the Himalaya in Tibet. Like other rivers in Nepal, the Bhote Kosi is prone to glacial lake outburst floods, and geologists have found evidence of previous events in 1935 and 1964… By the time we got to Lamosangu and approached the Sun Kosi intake barrage, the road abruptly vanished at almost the exact spot near Jure where Saturday morning’s deadly landslide occurred.” The 1981 experience is based on Kunda’s reporting experience as a young reporter.

Interestingly, Kunda writes, “As night fell, the water level was down by 2m and falling.” This is good sign.

PS 17: 1830 hours IST on Aug 5, 2014: Some worrying sings:

There is a bit of worrying sign that since last 18 hours, the water flow in Sunkoshi at Pachuwarghat, which is the nearest downstream measuring point, has been almost continuously decreasing from around 401 cumecs to now around 346 cumecs (the peak y’day morning was 569 cumecs, the bottom was 214 cumecs at 17 hrs on Aug 2) when the inflow to the landslide dam as measured at Bahrabise site, the nearest upstream site is same or in fact increased. This seems to suggest that water outflow from the landslide dam has decreased and this in turn could mean more water is getting collected behind the dam. This could possibly due to more landslide fall?

It seems (see: http://www.ekantipur.com/2014/08/05/top-story/army-carries-out-controlled-blast-at-sunkoshi-river/393184.html) Nepal Army carried out another explosion today: “In an attempt to speed up the outflow of water from the dam created after landslide in the Sunkoshi River, security personnel on Tuesday carried out a controlled explosion. A temporary dam was formed in the river in Jure of Sindhupalchok district after a massive landslip early on Saturday morning, stoking fears in the human settlements downstream. Chief District Officer Gopal Prasad Parajuli said the attempt was made to drain out the water, according to the suggestions of geologists, meteorologists and other experts, after the water level in the dam did not decrease even four days after the landslide. “A low intensity blast was carried out because powerful bombs will be risky,” said Parajuli.”

“Arun Shrestha, manager of ICIMOD’s river basin program told Circle of Blue that three main questions must be answered in the next few days: Will the hillside collapse again? What can be done to stabilize the slope? How stable is the landslide dam across the Sun Koshi River?” The nature of the dam, comprised of rock, mud, and sediment, is the greatest concern, Shrestha said. Shrestha mentioned the catastrophic June 2013 floods in Uttarakhand as another example of natural hazards limiting national hydropower plans. But cautious development in Nepal will be easier wished than accomplished, asserted Gyawali, the former water resources minister.

When asked which authorities were responsible for approving hydropower permits, Dipak Gyawali scoffed at the question. “I am afraid these questions arise in your mind conflating Nepal with Norway,” he wrote in an email. “We have a dominating informal sector where policies are made and decisions are taken at the household level. Yes, government has policies. Can they effectively implement it? Well, more easily on the moon than in next-to-inaccessible Nepali hinterlands.” If the authorities want, the Sun Koshi example can serve as a guide for hydropower development, said Gyawali, who is now research director of the Nepal Water Conservation Foundation. “These bishyaris keep happening all the time,” Gyawali said, referring to the floods from landslide dams. “Nepal is better off developing small hydropower plants across the country. If we try to build one single plant, we’re putting a larger risk on the table. Many smaller ones cannot all be knocked out.”

Petley, the Durham University landslide expert, said that more research on natural hazards in the Himalayas is needed. “The Himalayan landscape needs to be managed very carefully,” Petley said. “There is too much indiscriminate development.”

This is clearly WRONG in this report: “The hydropower stations along the river do not use large dams. Rather, they are small facilities, no more than 45 megawatts, that divert a portion of the river’s flow to generate electricity before returning it to the channel downstream.” Most of these projects have large dams and have huge impacts locally.

This is a most serious development. Thanks Himanshu /SANDRP for the early alert on this when most mainstream media seems to be unaware of this development. Hope this alerts the authorities too. – Shripad

Landslides are natural to immature Himalayan drainage under heavy rainfall. Formation of land slide lakes, temporary to permanent, and subsequent breaching ending in disasters are known. Man made dams and embankments with or without proper drainage network behind embankments deepen the tragedy. is it possible to predict where all the embankments may get breached and the consequences ? The people still living in between the embankments would be the worst sufferers on account of heavy flows from the landslide dam.

Yes, those between the embankment will be the first sufferers and if the embankment breaches outsiders too will be. Dinesh Kumar Mishra tells me that the site at Kusaha where the Aug 2008 breach occurred is possibly the weakest point. Bihar govt says that if the flow is above 250 000 cusecs than several points are vulnerable. But the flood control department of Bihar govt Should be in best position to make specific prediction. They have started relocating people from within embankments, but it is not clear how many have been.

The landslide across Sunkoshi, can have devastating impact on the downstream areas in Nepal and India. Governments of both the countries need to be watchful. It is high time that an international disaster management group is formed to help each other in the Himalayan kingdom.